Polymerization of 1,3‐dienes and styrene catalyzed by cationic allyl Ni(II) complexes

Abstract

Polymerizations of 1,3-dienes using in situ generated catalyst [(2-methallyl)Ni][B(Ar F ) 4 ], 6, (Ar F ¼ 3,5-bis(trifluoromethyl)phenyl) as well as [(2-methallyl)Ni(mes)][B(Ar F ) 4 ], 14, (mes ¼ mesitylene) are reported. Highly sensitive complex 6 polymerizes butadiene (BD) at -30 C to yield polybutadiene with a M n of ca. 10 K and 94% cis-1,4-enchainment while less reactive isoprene (IP) was polymerized at 23 C to yield polyisoprene with M n ca. 7 K. Complex 6 was also shown to polymerize a functionalized diene, 2,3-bis(4-trifluoroethoxy-4oxobutyl)-1,3-BD, to polymer with M n ¼ 113 K. The stable and readily isolated arene complex 14 initiates BD and IP polymerizations at somewhat higher temperatures relative to 6 and delivers polymers with higher molecular weights. Complex [(allyl)Ni(mes)][B(Ar F ) 4 ], 13, catalyzes polymerization of styrene to yield polystyrene with high conversion, M n 's ¼ ca. 6 K and MWD ¼ 2. The p-benzyl complex [(g 3 -1-methylbenzyl)Ni(mes)] [B(Ar F ) 4 ], 19, was detected as an intermediate following chain transfer by in situ NMR studies.

Ni(II) and Pd(II) complexes bearing novel bis(β‐ketoamino) ligand and their catalytic activity toward copolymerization of norbornene and 5‐norbornene‐2‐yl acetate combined with B(C6F5)3

“…The vinyl‐type PNB can be obtained through Ziegler‐Natta,22–25, 30–32 metallocene,12, 29 rare earth metal,26, 33, 41 and late transition metal catalysts 13–21, 27, 28, 34–40, 42–47. The late transition metal catalysts are simple to synthesize and show more stable to polar NB detectives.…”

Preparation of highcis‐1,4 polyisoprene with narrow molecular weight distribution via coordinative chain transfer polymerization

“…The solution process also restricts the polymerization ether in high temperature for the essential solubility of the long ethylene sequences of block copolymer, or short polymerization time before precipitation of the polymer. Third, only a few catalyst systems have been described to meet these requirements so far 6, 7, 12–20…”

Fluoroarene Complexes with Small Bite Angle Bisphosphines: Routes to Amine–Borane and Aminoborylene Complexes

“…These studies showed that complexes could be accessed in situ for n = 0–3 (Scheme b), whereas for more highly fluorinated analogues ( n = 4–6) the reduced coordinating ability of the arene means that π complexation of the [BAr F 4 ] – counterion becomes more favourable, and the zwitterionic complex [Rh( i Bu 2 PCH 2 CH 2 P i Bu 2 ){η 6 ‐(3,5‐(CF 3 ) 2 C 6 H 3 )BAr F 3 }] was observed as the sole product. Similar π‐coordination of [BAr F 4 ] – is now well established , …”

“…Similar π-coordination of [BAr F 4 ] is now well established. [16,[20][21][22][23] With these observations in hand, we speculated that in order to synthesise an amine-borane complex with small bite angle bisphosphine supporting co-ligand a very weakly ligating fluoroarene would be needed to be coupled with manipulation of the anion to avoid zwitterion formation. In this contribution we demonstrate that Rh-complexes with the exceptionally small bite angle Cy 2 PCH 2 PCy 2 (dcpm) ligand [13,24] combined with moderately fluorinated arenes can be accessed using the [Al{OC(CF 3 ) 3 } 4 ]anion, thus providing a route to synthetically useful quantities of a trifluorobenzene complex (Scheme 1c).…”